1. Technical Field
This invention relates to a sheet thickness sensor, and more particularly to a device or an apparatus for sensing a thickness of articles as conveyed or fed over a conveyor path or the like.
2. Prior Art
Recently, a large amount of sealed documents such as direct mail, debit notes and the like are conveyed or mailed from businesses to customers by mail and the like. It is required to check such documents, with respect to weight and/or thickness.
It is generally practiced to mail a large number of documents such a printouts, invoices, and direct mails in the same format to addressees. As illustration of mail processing, the example of inserting and sealing the invoices into each envelope may be explained as follows.
Usually, debit notes in the form of a continuous sheet containing the address and required information with each document being cut and folded to a predetermined size and placed in an envelope together with necessary enclosures by utilizing a mail forming apparatus. Such a process is effected automatically. To minimize errors in forming the envelopes, there has been utilized a thickness detecting device for measuring the thickness of each of the envelopes being conveyed on a transporting passage.
However, prior art thickness detecting devices are not satisfactory in terms of reliability and applicability.
An object of the invention is to provide a thickness detecting device which can accurately detect the thickness of an article being conveyed on a transporting passage at a desired location.